Fire-suppression may refer to a use of agents such as gases, liquids, solids, chemicals and mixtures thereof to extinguish combustion. Fire-suppression systems generally use a “total flooding” or a “non-total flooding” method to apply an extinguishing agent in an enclosed volume. The total flooding or the non-total flooding method may achieve a concentration of the extinguishing agent as a volume percent to air of the extinguishing agent sufficient to suppress or extinguish a fire.
Existing all-cargo aircraft generally have class E cargo compartments that do not have active fire-suppression agent capability. A fire on these aircraft is generally controlled by shutting off ventilation into the class E cargo compartment, depressurizing the aircraft, and landing at a nearest suitable airport. While the aircraft is depressurized, an active flame is suppressed due to a low oxygen partial pressure above 6.1 km (20,000 feet). Although the fire is suppressed at altitudes above 6.1 km (20,000 feet), the fire may continue to smolder.